Clinical and electrophysiologic data recorded in patients with Fisher syndrome characterized by ophthalmoplegia, ataxia, and areflexia are presented. Cases with limb weakness or pleocytosis in the CSF were excluded, according to Fisher. Ten patients were selected. All had hand and foot numbness. A large amount of protein without cell reaction was found during the third week of illness in serial CSF examinations. EMGs showed very slight limb involvement without spontaneous activity, and in most cases, facial muscles exhibited a denervation pattern. Distal motor nerve conduction velocity on limbs and F wave latencies were normal, whereas the sensory nerve action potentials were altered in all but one case when tested (seven out of eight cases). By means of blink reflex study performed in four patients, no significant pattern of brainstem dysfunction was discovered. The authors discuss the preeminent role of peripheral nerve lesions with regard to the ataxia and ophthalmoplegia.